猫红核小细胞部向三叉神经感觉核簇的投射——WGA-HRP顺行追踪法研究

将WGA—HRP溶液注入于猫红核吻侧段,顺行追踪了红核向三叉神经感觉核簇投射的纤维行径及终未分布,发现红核有下行纤维投射于对侧三叉神经感觉核簇各亚核。结合作者等既往的研究肯定此投射的起源为对侧红核吻侧2/3段小细胞部背外侧的中、小型细胞群。投射终末以尾侧亚核的深层相当于脊髓背角Ⅳ、Ⅴ、Ⅵ层的地区最为密集,特别是V层最为集中。鉴于此区又是三叉神经初级传入纤维的投射区,还有三叉神经二级感觉(特别是痛觉)神经元胞体及树突的存在,因而作者等认为此区应属于尾侧亚核的一个部分,而不应将之归属于网状结构。红核向此区的投射可能和三叉初级传入纤维之间或两者与二级感觉神经元之间有汇聚的关系。这种汇聚可能对口面部的感觉特别是痛觉的传递产生某种调节作用。

THE PROJECTION FROM THE PARVOCELLULAR PART OF THE RED NUCLEUS TO THE TRIGEMINAL SENSORY COMPLEX IN THE CAT-A STUDY USING THE ANTEROGRADE TRACING TECHNIQUE WITH WGA-HRP

WGA--HRP solution was injected into the rostral half of the red nucleus of 10 cats and the labeled projection fibers to the trigeminal sensory nuclear complex were traced anterogradely. The result was that in all parts of the contralateral trigeminal sensory complex descending fibers from the red nucleus were observed, which, according to our previous study, arised from the parvocellular portion of the rostral 2/3 of the red nucleus. The labeled terminal branches in the subnucleus caudalis of the trigeminal spinal nucleus were distributed in its deeper part, corresponding to Laminae Ⅲ-Ⅵ of the spinal dorsal horn, with higher concentration in Lamina V. The authors support the view that this area, adjacent to the subnucleus caudalis, receiving primary afferent terminals and having sensory neurons, especially pain neurons, which pro- ject to the thalamus, is more proper to be taken as a part of the subnucleus caudalis than as a part of the reticular formation. Projection fibers from the red nucleus must come into contact with one or more of the structures here, including the primary afferents, the secondary sensory neurons, or interneurons, so that the descending impulses from the red nucleus might converge with the primary afferent inputs and play certain role of modulation on the transmission of oro--facial sensations,especially pain.